1. Technical Field
The technology disclosed herein relates to a drive unit including a vibratory actuator having an actuator body and driver elements.
2. Background Art
Drive units including vibratory actuators for use in various electric devices have been conventionally known (e.g., Japanese Patent Publication No. 2008-193874).
A vibratory actuator associated with a drive unit described in Japanese Patent Publication No. 2008-193874 includes an actuator body configured with a piezoelectric element, and a driver element provided on the actuator body is disposed so as to contact a rotor, which is a movable element. This drive unit induces vibration in the actuator body by applying two alternating current (AC) voltages having a same frequency and different phases to the piezoelectric element in the actuator body, thereby causing the driver element to move accordingly. In doing so, a driving force is transmitted from the driver element to the rotor, and thus the rotor is driven in a predetermined direction. In this regard, the drive unit controls the rotation speed of the rotor by adjusting the phase difference between the two AC voltages depending on the deviation between a target and an actual rotation speeds of the rotor.